Conventionally, photocurable compositions that can be cured by irradiation with light are widely used for forming a film portion, an applied portion, or a printed portion in a pressure-sensitive adhesive (adhesive), a sealant, a coating material, an ink, and the like. A polyfunctional polymer having a polymerizable unsaturated group in a side chain via a urethane bond is sometimes used as a raw material for the photocurable composition for these uses. As a method for producing the polyfunctional polymer, a method for reacting a polymer having a hydroxy group with a monomer having an isocyanate group using an organotin compound as a catalyst has been suitable (see, for example, Patent Documents 1 and 2).
However, the organotin compound is said to have effects on the human body and the environment in recent years. Its use is restricted by the REACH regulation, and is particularly severely restricted in an electronic material field and a semiconductor producing field.
As a method for using a compound other than the organotin compound as a catalyst, a method for using a titanium complex, a zirconium complex, or the like as a catalyst has been known (see, for example, Patent Document 3).